Fuel injectors typically use a check valve in the fuel path between an injector pumping element and an injector nozzle element. The check valve is designed to prevent a back flow of fuel into the pumping element once the delivery of fuel is complete. The check valve also prevents combustion gases from entering the pumping element in the event such gasses pass through valve associated with the nozzle element.
In engines with high ratings, flow irregularities often referred to as knocking has occurred in some injectors during high output operation. This knocking is believed to be due to unstable motion of the check valve disk during the pumping stroke when the disk should be seated on a ledge spaced from the valve seat. It is believed that rapid radial outflow of fuel over the upper side of the disc to passages through the disk, typically in the form of scallops at edges of the disk, causes momentary reductions in pressure above the disk sufficient to allow system pressure below the disk to lift it erratically from the ledge. In an effort to reduce knocking, attempts have been made to reduce the radial flow path of fuel over the top surface of the check valve disk.
U.S. Pat. No. 5,328,094, the disclosure of which is expressly incorporated herein in its entirety by reference, discloses a fuel injector check valve having a plurality of equally spaced holes. The plurality of holes are equally spaced in a ring near the fuel delivery opening.
U.S. Pat. No. 5,797,427, the disclosure of which is expressly incorporated herein in its entirety by reference, discloses a fuel injector check valve having a plurality of notches or slots. The notches or slots have inner edges that are concave in shape and are located near the fuel delivery opening to reduce the radial distance between the fuel delivery opening and the notches.
While these prior attempts may have somewhat reduced flow irregularities, they have reduced the seal area and require relatively large loads to open. Accordingly, three is a need in the art for an improved fuel injector check valve.